Olefin disproportionation catalyst and process for using same

ABSTRACT

An olefin disproportionation catalyst is provided comprising a minor amount of tungsten oxide or molybdenum oxide, about 0.01 to 1 weight percent of fluorine, the remainder of the catalyst substantially being silica. The process of using this catalyst to disproportionate unsaturated materials is also claimed.

United States Patent [191 Regier 1 1 Dec. 2, 1975 1 1 OLEFINDISPROPORTIONATION CATALYST AND PROCESS FOR USING SAME [75] Inventor:Robert B. Regier, Bartlesville, Okla.

[73] Assignee: Phillips Petroleum Company,

Bartlesville, Okla.

[22] Filed: May 24, 1973 [2]] Appl. No: 363,481

Related U.S. Application Data [62] Division of Scr. No. 129,201, March29, 1971, Pat.

[52] U.S. Cl 260/683 D; 260/465.9; 260/653.3', 260/666 A; 260/668 A;260/677 R; 260/672 [51] Int. Cl. C07c 3/62 [58] Field of Search 260/683D, 680 R, 677 R, 260/465.9. 653.3, 666 A. 678

[56] References Cited UNITED STATES PATENTS 2,760,907 8/1956 Attane eta1. 208/136 Primary Examiner-Delbert E. Gantz Assistant ExaminerC. E.Spresser [57] ABSTRACT An olefin disproportionation catalyst is providedcomprising a minor amount of tungsten oxide or molybdenum oxide, about0.01 to 1 weight percent of fluorine, the remainder of the catalystsubstantially being silica. The process of using this catalyst todisproportionate unsaturated materials is also claimed.

11 Claims, No Drawings OLEF IN DISPROPORTIONATION CATALYST AND PROCESSFOR USING SAME This is a division of application Ser. No. 129,201, filedMar. 29, 1971, now US. Pat. No. 3,761,427.

BACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates to disproportionation of disproportionatable unsaturatedmaterials. In a further aspect, this invention relates to an improvedcatalyst for the olefin disproportionation reaction.

2. Description of the Prior Art Numerous catalysts have recently beendiscovered which effect the olefin disproportionation reaction ofolefinic unsaturated hydrocarbons. The reaction can be visualized as thebreaking of two existing double bonds between first and second carbonatoms, and between third and fourth carbon atoms, respectively, and theformation of two new double bonds, such as between the first and thirdcarbon atoms and the second and fourth carbon atoms, respectively,wherein the new double bonds can be on the same or different molecules.The reaction can be visualized by using a mechanistic scheme involving acyclobutane intermediate wherein two unsaturated pairs of carbon atomscombine to form a 4-center intermediate which then disassociates bybreaking either set of proposing bonds. This reaction can beillustratedby the following formulas:

The above reaction has been described by various terms other than olefindisproportionation. Among those terms utilized are the olefin reaction,"olefin dismutation, mutual cleavage, transalkylidenation, and olefinmetathesis. Through this specification and claims, the term olefindisproportionation is used as a matter of choice and is deemed to beequivalent to the above-mentioned terms. In addition, it has recentlybeen discovered that the disproportionation reaction can be applied tomaterials other than olefinically unsaturated hydrocarbons. Accordingly,it has been reported that acetylenically unsaturated hydrocarbons andolefinic materials which contain functional groups such as nitrilegroups or fluoro groups also undergo this type of reaction.

Among the numerous catalyst systems which have been reported to effectthe disproportionation reaction are those of US. Pat. No. 3,261,879,Banks (1966); US. Pat. No. 3,365,513, Heckelsberg (1968). TheHeckelsberg patent discloses that tungsten oxide on silica is a suitabledisproportionation catalyst.

It has also been reported in the prior art that the presence of doublebond isomerization activity in a disproportionation reaction zone isadvantageous in that it increases the rate of conversion and makespossible the production of a wider range of reaction products as well asproducts not otherwise obtainable. For example the presence of suchdouble bond isomerization activity greatly increases thedisproportionation rate of symmetrical olefins such as butene-2. Inaddition, the isomerization activity permits the exhaustive cleavage ofhigh molecular weight monoolefins with ethylene to lower molecularweight monoolefins such as propylene and isobutene. British Pat. No.1,205,677, published Sept. 16, 1970, provides a catalyst which comprisesan olefin disproportionation component and a Group VIII noble metaldouble bond isomerization component, i.e., palladium, platinum, orruthenium. Another catalyst system which accomplishes these results isobtained by physically mixing about 6 parts of catalytic magnesium oxidewith about 1 part of tungsten oxide on silica catalyst. Other catalystswhich have been developed include those obtained by copromoting anolefin disproportionation catalyst such as tungsten oxide on silica withminor amounts of the oxides of niobium, tantalum, or vanadium to providethe double bond isomerization activity.

OBJECTS OF THE INVENTION It is an object of this invention to provide acatalyst for the disproportionation of disproportionatable materialswhich also has double bond isomerization activity. It is a furtherobject of this invention to disproportionate disproportionatablematerials by contacting the feed material with a catalyst havingactivity for both disproportionation and double bond isomerization.Other objects and advantages of the invention will be apparent from acareful reading of the summary of the invention, the detaileddescription of the invention, the examples, and the claims.

SUMMARY OF THE INVENTION It has now been found that double bondisomerization activity can be introduced into a silica-containing olefindisproportionation catalyst by pretreating the silica with a fluoridingagent. Accordingly, the catalyst of the invention comprises about 0.1 toabout 25 weight percent of tungsten oxide or molybdenum oxide ormixtures thereof, from about 0.01 to about 1 weight percent of fluorine,the remainder of said composition substantially being silica. Theprocess of my invention comprises converting disproportionatable feedmateri als by contacting the feed with the above-described catalyst.

DETAILED DESCRIPTION OF THE INVENTION The catalyst of the invention canemploy any suitable catalytic grade of silica. Material such as silicagel, silica aerogels, flame-hydroly2ed silica gel and the like can beemployed. Generally, such catalytic materials have a surface area of atleast about 1 rn /g. The silica employed can contain minor amounts ofother materials such as sodium or aluminum so long as these materialsare of a nature or in an amount which does interfere with the conversionreaction.

The catalyst of the invention is prepared by contacting theabovedescribed catalytic silica with a suitable fluoriding agent underconditions such that a substantial amount of surface hydroxyl groups ofthe silica are replaced by fluorine leaving about 0.01 to about 1.0weight percent fluoride residue on the silica. Any fluorine-containingmaterial which is capable of effecting such a substitution can be used.The fluoriding agent is preferably non-acidic or only mildly acidicbecause highly acidic fluorine materials, such as HF, are not suitablein that they result in substantial loss of silica from the catalyst bysolubilization and/or volatilization. Inaddition, highly acidicfluoriding agents generally have an adverse effect upon the surface areaof the catalyst.

Suitable fluoriding agents include neutral fluoride salts such asammonium and alkali metal fluorides. Non-limiting examples of theseagents are sodium fluoride, potassium fluoride, lithium fluoride, andthe like. Fluoriding agents such as ammonium and alkali metal bifluoridesalts, for example, sodium bifluoride, potassium bifluoride, andthe'like can also be used. In addition, fluoriding agents such asammonium silicofluoride, sodium silicofluoride, fluorosilicic acid, andthe like can be employed.

The silica may be fluorided by any suitable techniques such as bycontacting the silica with an aqueous solution of the soluble fluoridingagent at a temperature and a time sufficient to substitute a substantialamount of the hydroxyl groups on the surface of the silica. The abovetreatment is conducted for a sufficient length of time and at theselected temperature to leave a fluoride residue on the silica rangingfrom about 0.01 to about 1.0 percent based on the silica. When neutralsolutions of the fluoriding agent are employed, no dissolution of thesilica to compound such as H- ,SiF, is believed to occur. However, whenbifluorides are used as fluoriding agents, the time of contact of thebifluoride solution with the silica should be short enough to avoidexcessive dissolution of the silica. Concentration of the fluoridingagent in the aqueous fluoriding solution can range from about 1 weightpercent to saturation, and relatively concentrated solutions arepreferred to facilitate the rapid replacement of the surface hydroxylgroups on the silica. Generally, the time of contact can range fromabout 1 minute to about several hours and the temperature can be in therange of from about to about 50C 32l22F).

After contact with the fluoridingagent, the silica is washed with waterto remove the excess fluoriding reagent and to remove any residualalkali metal ions if alkali metal salts were used. After washing, thefluorided silica is then dried to remove substantially all the water andto insure that the fluoride will be fixed to the surface. The silica isgenerally dried at a temperature in the range from about ll0l50C(230-302F).

The above-described silica, containing fluorine, is then impregnatedwith suitable amounts of a soluble tungsten and/or molybdenum compound.The amount of the soluble promoter compound is sufficient to provide atungsten oxide and/0r molybdenum oxide content in the catalyst aftercalcination of from about 0.1 to about 25, preferably from about 1 toabout weight percent, based on the total weight of the composition. Theimpregnation is carried out using any suitable technique and anysuitable tungstenand/or molybdenum containing impregnating agent whichis convertible to the corresponding oxide on calcination. TheHeckelsberg patent, discussed supra, discloses suitable promotercompounds of tungsten and molybdenum which can be employed to impregnatethe fluorided silica.

After incorporation of the tungsten or molybdenum compound, or mixturesthereof, the catalyst composition is again dried and then calcined toactivate it for the conversion process. The calcination can take placeat temperatures in the ran geof 600l500F. although temperatures in therange of 900l200F. are preferred for optimum activity. The calcinationgenerally takes place in the presence of an oxygen-containing gas suchas flowing dry air. However other suitable gases can also be used. Forexample, the catalyst can be activated in nitrogen or helium, or amixture of other suitable gases. If desired, more than one activatinggas may be used sequentially during the activation. In addition.

activation can also occur in an evacuated chamber. The time for the.activation will generally depend upon the type of activation employedbut will generally range from about 0.1 to about 25 hours. Aftercalcination, the catalyst can be flushed and/or contacted with othergases which do not interfere with the subsequent conversion process. Thefinished catalyst can be in any convenient form such as pills, powder,agglomerates, extrudates, and the like.

The unsaturated feed stocks which can be converted by this catalyst areany of those which are convertible by the prior art olefindisproportionation catalyst. Thus the present invention will convert thesame feeds in the same way to obtain essentially the same products asthe more well known tungsten oxide on silica catalysts or molybdenumoxide on silica catalysts. Such feeds, therefore, will includedisproportionatable monoolefins and polyenes both cyclic and acyclic,branched and unbranched, and mixtures of these with ethylene. Alsoincluded are those disproportionatable olefinic materials which containfunctional groups such as nitrile groups or fluoro groups. Alsoapplicable are the acetylenicallyunsaturated hydrocarbons which aredisproportionatable with these olefin disproportionation catalysts. Theabove-described unsaturated feed stocks are converted by the process ofthe present invention by contact with the catalyst under suitablereaction conditions, either batchwise or continuously, using anysuitable mode of contact or reaction apparatus. If desired, the feedstocks can be diluted with inert diluents or solvents such as saturatedhydrocarbons. Any convenient pressure can he used and pressures in therange of about 0-2000 psig are generally suitable. In a continuousprocess, the feed rate will vary according to the feed stock beingconverted to the desired degree of conversion, but it will gcnerallybein the range of about 0.5 to about 1000 WHSV. In batch operations, thereaction time can range from about 0.1 to about 20 hours. The reactiontemperature can be varied from about 400F. to about I IOOF. Whenmolybdenum oxide is used, the preferred temperature is 575-840F. foroptimum activity and when tungsten oxide is used, the preferredtemperature is 600-900F. for optimum activity.

After leaving the reaction zone, the reaction products can be separatedby any conventional means and the desired products isolated andrecovered. Uncon verted and incompletely converted feed materials can berecycled through the reaction zone if desired for further conversiontherein.

The above described invention is illustrated below by the followingExample. However, it is understood that the data of the Example is forthe purpose of illustration only and it should not be considered tolimit the scope of the invention as described above.

EXAMPLE Two catalysts were prepared, at the same time, which wereidentical except for the fluoriding treatment. The silica used for thepreparation of the catalyst was a commercial catalytic grade material(Davison Grade 59) which had a surface area in the range of 240-298 m /gand which had a pore radius in the range of 60-62 angstroms. A 5.0 gquantity of the silica (20+40 mesh) was slurried with 10 g of aqueous 30weight percent ammonium fluoride solution. The silica was allowed tosoak for 30 minutes after which it was washed thoroughly with water andthen dried for 30 minutes at 125C. (275F.) to remove the water and tofix the fluoride. As treated, this material contained 0.02 weightpercent fluorine.

After the drying, the fluorided silica was contacted with ml of anaqueous ammonium metatungstate solution containing 0.125 g of W0 Theimpregnated catalyst was dried, then activated by calcination in flowingair at 500C. (932F.) for about 1 hour. It was then flushed with drynitrogen gas. The dried catalyst contained about 2.5 weight percent W0 Asimilar catalyst was prepared for comparison with identical steps exceptthe fluoriding treatment was omitted.

Each of the above-prepared catalysts was used in an olefindisproportionation conversion reaction wherein l-butene feed wasdisproportionated to other olefins of both higher and lower molecularweight at 0 psig, at 7 WHSV, and at two different temperatures, 450C.(842F.) and 500C. (932F.). The results of these runs are shown in theTable below.

It is apparent that the catalyst prepared from the fluorided silicaeffected higher conversions than the non-fluorided control catalyst; itwas also much more active for double bond isomerization, as shown by theincreased selectivity to propylene and pentenes. The primary productsfrom the disproportionation of lbutene, where there is little or nodouble bond isomerization activity, is ethylene and 3-hexene. However,when double bond isomerization activity is present, at least a portionof the lbutene is isomerized to 2- butene resulting in substantialamounts of olefinic products such as propylene and pentenes. Such wasthe case with the runs using the invention fluorided catalysts.

Despite the enhanced double bond isomerization activity of the inventioncatalyst, it exhibited no detectable skeletal isomerization.

Reasonable modifications and variations in the invention as describedherein will be apparent to those skilled in the art without departingfrom the spirit and scope of the invention described above.

I claim:

1. The process of disproportionating a disproportionatable feed materialselected from the group consisting of disproporti'onatable cyclic andacyclic, branched and unbranched monoolefins and polyenes or mixtures ofthese monoolefins or polyenes with ethylene by contacting said materialwith a catalyst consisting essentially of about 0.1 to about 25 weightpercent of tungsten oxide, molybdenum oxide, or mixtures thereof, about0.01 to about 1.0 weight percent of fluorine, the remainder of saidcomposition being substantially silica, the amount of fluorine beingbased on the weight of silica, and the amount of promoter material beingbased on the total weight of the composition.

2. A process according to claim 1 wherein the material is contacted withthe catalyst at a temperature in the range of about 400 to about 1100F.

3. A process according to claim 1 wherein the material is contacted witha catalyst in a continuous operation at a feed rate from about 0.5 toabout 1000 weight hours space velocity and a pressure in the range offrom about 0 to about 2000 psig.

4. A process according to claim 1 wherein the material is contacted withthe catalyst in a batch operation at a reaction time of from about 0.1to about 20 hours.

5. A process according to claim 1 wherein the catalyst contains anamount of tungsten oxide, molybdenum oxide, or mixtures thereof, whichis from about I to about 15 weight percent.

6. A process according to claim 1 wherein the silica prior toassociation with the promoter material and fluorine has a surface areaof at least about 1 m /g and is a silica gel, silica aerogel. or flamehydrolyzed silica gel.

7. A process according to claim 1 wherein said catalyst is prepared byl. contacting a catalytic grade silica with a non-acidic fluoridingagent under conditions such that a substantial amount of the surfacehydroxyl groups of the silica are replaced by fluorine,

2. washing the fluorided silica of step (1) to remove excess fluoridingagent,

3. drying the washed fluorided silica of step (2),

4. impregnating the dried fluorided silica of step (3) with a compoundof tungsten, molybdenum, or mixtures thereof which is convertible to theoxide of tungsten or oxide of molybdenum or mixtures of said oxides oncalcination,

5. drying the composite from step (4), and

6.- calcining the composite at a temperature of from about 600 to aboutl500F. to activate the catalyst.

8. A process according to claim 7 wherein the material is contacted withthe catalyst at a temperature in the range of about 400 to ll00F.

9. A process according to claim 8 wherein the catalyst contains anamount of tungsten oxide, molybdenum oxide, or mixtures thereof, whichis from about 1 to about 15 weight percent.

10. A process according to claim 1 wherein said fluorine is provided bycontacting the silica with ammonium fluoride.

11. A process according to claim 10 wherein said catalyst consistsessentially of tungsten oxide, fluorine and silica.

1. THE PROCESS OF DISPROPORTIONATING A DISPORPORTIONATABLE FEED MATERIALSELECTED FROM THE GROUP CONSISTING OF DISPORPORTIONATABLE CYCLIC ANDACRYLIC, BRANCHED AND UNBRANCHED MONOOLEFINS AND POLYENES OR MIXTURES OFTHESE MONOOLEFINS OR POLYENES WITH ETHYLENE BY CONTACTING SAID MATERIALWITH A CATALYST CONSISTING ESSENTIALLY OF ABOUT 0.1 TI ABOUT 25 WEIGHTPERCENT OF TUNGSTEN OXIDE, MOLYBDENUM OXIDE, OR MIXTURES THEREOF, ABOUT0.01 TO ABOUT 1.0 WEIGHT PERCENT OF FLUORINE, THE REMAINDER OF SAIDCOMPOSITION BEING SUBSTANTIALLY SILICA, THE AMOUNT OF FLUORINE BEINGBASED ON THE WEIGHT OF SILICA, AND THE AMOUNT OF PROMOTER MATERIAL BEINGBASED ON THE TOTAL WEIGHT OF THE COMPOSITION.
 2. A process according toclaim 1 wherein the material is contacted with the catalyst at atemperature in the range of about 400* to about 1100*F.
 2. washing thefluorided silica of step (1) to remove excess fluoriding agent, 3.drying the washed fluorided silica of step (2),
 3. A process accordingto claim 1 wherein the material is contacted with a catalyst in acontinuous operation at a feed rate from about 0.5 to about 1000 weighthours space velocity and a pressure in the range of from about 0 toabout 2000 psig.
 4. A process according to claim 1 wherein the materialis contacted with the catalyst in a batch operation at a reaction timeof from about 0.1 to about 20 hours.
 4. impregnating the dried fluoridedsilica of step (3) with a compound of tungsten, molybdenum, or mixturesthereof which is convertible to the oxide of tungsten or oxide ofmolybdenum or mixtures of said oxides on calcination,
 5. drying thecomposite from step (4), and
 5. A process according to claim 1 whereinthe catalyst contains an amount of tungsten oxide, molybdenum oxide, ormixtures thereof, which is from about 1 to about 15 weight percent.
 6. Aprocess according to claim 1 wherein the silica prior to associationwith the promoter material and fluorine has a surface area of at leastabout 1 m2/g and is a silica gel, silica aerogel, or flame hydrolyzedsilica gel.
 6. calcining the composite at a temperature of from about600* to about 1500*F. to activate the catalyst.
 7. A process accordingto clAim 1 wherein said catalyst is prepared by
 8. A process accordingto claim 7 wherein the material is contacted with the catalyst at atemperature in the range of about 400* to 1100*F.
 9. A process accordingto claim 8 wherein the catalyst contains an amount of tungsten oxide,molybdenum oxide, or mixtures thereof, which is from about 1 to about 15weight percent.
 10. A process according to claim 1 wherein said fluorineis provided by contacting the silica with ammonium fluoride.
 11. Aprocess according to claim 10 wherein said catalyst consists essentiallyof tungsten oxide, fluorine and silica.